1. Field of Invention
The present invention relates to planar solid oxide fuel cells and, more particularly, to glass-ceramic sealant for planar solid oxide fuel cells.
2. Related Prior Art
Solid oxide fuel cells are high-temperature fuel cells of high generation efficiencies. Among the solid fuel cells, planar solid oxide fuel cells include the simplest structures, provide the highest generation efficiencies and involve the lowest working temperatures. Therefore, the planar solid oxide fuel cells are the focus of the research and development of solid oxide fuel cells.
A planar solid oxide fuel cell includes a PEN and an anode, a cathode, a solid electrolyte and a bi-polar inter-connector stacked on one another. The anode, the cathode and the solid electrolyte together are called the “PEN.” The anode, the cathode and the solid electrolyte are made of ceramics. The bi-polar inter-connector is made of stainless steel. These components of the planar solid oxide fuel cell are joined together by sealant. The thermal expansion coefficients of the sealant are very different from the thermal expansion coefficients of the components. The temperature differs from point to point in the sealant and the components. Hence, there is considerable thermal stress in the planar solid oxide fuel cell. Such thermal stress might cause the sealant to crack and the components to peel from one another. The components might be exposed and/or damaged. The generation efficiency of the planar solid oxide fuel cell might be reduced. In the worst scenario, the planar solid oxide fuel cell might be out of order.
The present invention is therefore intended to obviate or at least alleviate the problems encountered in prior art.